1. Field of the Invention
This invention relates to a knockdown type filtering device for use in a water tank for fish such as goldfish, tropical fish and the like.
2. Description of the Prior Art
In prior art filtering apparatus used in a water tank for goldfish, tropical fish and the like, when the flow velocity of water to be filtered is increased in order to enhance the filtering ability, not only chlorellas required for raising fish but bacteria which eat vegetable plankton are destroyed to allow propagation of the vegetable plankton and as a result, the water in the water tank becomes impure, whereas when the flow velocity of water is adjusted, sufficient filtering action cannot be attained. In any case, it has been extremely difficult to raise fish for a long period of time while maintaining the water within the water tank clean without replacing the water or cleaning the tank.